We can simplify this expression by using the trigonometric identities:
sin^2a = 1 - cos^2acos^2a = 1 - sin^2a
Substituting these identities into the expression, we get:
(1-cos^2a)(1-cos^2a) - cos^2a*cos^2aExpanding,= 1 - 2cos^2a + cos^4a - cos^4a= 1 - 2cos^2a
Therefore, the simplified expression is 1 - 2cos^2a.
We can simplify this expression by using the trigonometric identities:
sin^2a = 1 - cos^2a
cos^2a = 1 - sin^2a
Substituting these identities into the expression, we get:
(1-cos^2a)(1-cos^2a) - cos^2a*cos^2a
Expanding,
= 1 - 2cos^2a + cos^4a - cos^4a
= 1 - 2cos^2a
Therefore, the simplified expression is 1 - 2cos^2a.